The invention relates to a serial changer which includes a cassette carriage provided with two clamping means for cassettes, the position of the first clamping means being determined by the height of the cassette while the position of the second clamping means is determined by the width of the cassette, and also includes a measuring device which determines the format of the cassette from the position of the clamping means.
A measuring device of this kind is known from German Patent Application No. P 31 22 723 (corresponding to U.S. Pat. No. 4,489,428). In the known device a measuring point is coupled to the two clamping means in such a manner that the change of its position in reaction to an adjustment of one clamping means deviates from that in reaction to a corresponding adjustment of the other clamping means. Thus, the position of the measuring point is an unambiguous measure of the width and the height of the inserted cassette (when standard cassettes are used), so that these dimensions can be determined by means of a single measurement.